The present invention is directed to an improved cap system for aluminum and/or steel bottles consisting of a plastic material cap that fits on to the neck of the aluminum or steel bottle in order to facilitate their sealing or leaktightness by adhesive means that could not be easily attached to the aluminum or steel material itself.
Therefore, this invention will be of special interest for the metallic container manufacturing industry, specifically in aluminum and/or steel, as well as for plastic material accessories in general.
The problems solved by the purpose of this invention lie in the difficulty of hermetically closing the mouth of the metallic bottles by adhesive means. This characteristic makes the use of aluminum or steel bottles difficult in certain applications, for example the bottling of foodstuff where the quality of the closing system is fundamental.
On the other hand, the mentioned adhesive sealing means of bottles by thermofusion are of common use as they especially adapt well to the closing necessities of plastic containers, which have been generally accepted during the last years basically due to their highly competitive cost.
However, another type of container, such as aluminum, which is able to be reused, or steel can also be competitive as they provide certain benefits, such as mechanical resistance or durability in the face of external agents, whilst the plastic containers do not have these characteristics.
In spite of this, one of the problems that has not been solved in a satisfactory way is the closing system, as it is not possible to apply certain sealing means by thermofusion in aluminum and/or steel containers which are applicable in plastic containers. Therefore, this invention intends to present an original solution, consisting in the creation of a plastic material cap which, together with a certain shape of the neck of an aluminum and/ or steel bottle, permits it to be placed and secured by means of a simple automated mechanical procedure, that is, it can be controlled by process control electronic devices such as sequencers or programmable robots. In this way the aluminum and/or steel bottle or container can be closed and sealed by thermofusion just like a plastic bottle.
The mentioned plastic material cap placed on the neck of the bottle is made of a plastic material cover with an inside diameter similar to the outside diameter of the neck of the bottle, formed by a projecting inside edge underneath the upper end of the cap. On the other hand, the thickness of the bottle walls is reduced at the upper end of the neck of the bottle near the mouth in order to permit its easy deformation once the mentioned plastic cap has been inserted. The end of the neck of the bottle may be deformed on the above described inside edge of the cap by inserting a suitable mold under pressure through the mouth.
In this way, the edge of the neck of the aluminum and/or steel bottle is expanded on top of the inside edge of the plastic material cap which is retained and pressed on the area of the shoulders of the bottle.
The resulting seal is completely leaktight between the aluminum and/or steel bottle and the plastic material cap due to the joint under pressure produced between the mentioned internal edge of the plastic material cap and the end area of the neck of the bottle, once this has been deformed by the previous mold inserted under pressure. This is obtained precisely due to the design of the cap, in which teeth have been provided on the contact surface between the previous inside edge and the end area or neck of the bottle so that the degree is leaktightness reached is complete.
The described cap defines an upper edge completely smooth of a plastic material that replaces the one of the original neck of the bottle. This can be easily used for applying elements and closing and sealing systems of the adhesive type by thermofusion, such as those used traditionally with plastic material bottles, without this entailing that the material used in manufacturing bottles (aluminum and/or steel) can cause any inconvenience in relation to the suitable closing and sealing method or system.
Likewise, in order to prevent the plastic material cap turning on the neck of the bottle, this has various outward projections consisting in punches made through the inside of the neck of the bottle that are fastened between the inside ribs of the cap arranged longitudinally on its internal face to reinforce its own structure.
In this way, the described plastic material cap is perfectly fastened to the neck of the aluminum and/or steel bottle and cannot be turned or removed, forming a leaktight joint between the end of the neck of the bottle and the plastic material end of the cap on which the closing and sealing by thermofusion can be carried out as if it were a plastic bottle.